1. Technical Field
The present invention relates to lighting assemblies in which one or more fixtures are positionally and/or structurally adaptable to provide optimal selection of desired illumination patterns. In its more specific aspects the present invention relates to mounting arrangements permitting adjustable mutual positioning of two or more reflected linear lighting fixtures, and to mounting arrangements for deflectors and diffusers on such fixtures.
2. Discussion of the Prior Art
Although the present invention has some applicability to lighting fixtures in general, it is primarily concerned with mounting arrangements for "linear reflected lighting fixtures", used outdoors, to provide optimum adjustability of the illumination pattern or display produced by those fixtures. The phrase "linear reflected lighting fixtures" as used herein is intended to refer to an elongated or linear source or lamp mounted in an elongated reflector (e.g. having a semicylindrical, parabolic, or other cross-section) which intensifies and gives direction to the light emitted from the lamp. Examples of such linear reflected lighting fixtures may be found in U.S. Pat. Nos. 2,964,616 (Seidman) and 4,464,707 (Forrest), the disclosures of which are expressly incorporated herein, in their entireties by this reference.
Optimal positional adjustability of individual linear reflected lighting fixtures, in an assembly of such features, is desirable for various applications. For example, for street and area lighting it is desirable to permit the individual fixture positions to be mutually adjusted, after installation, to effect maximum illumination coverage from the assembly. For display illumination it is desirable to maximize visibility of the display. In the latter application, for example, there may be a need to illuminate a sign, such as a billboard, with a first fixture while also projecting light through a translucent sign covering the light-emitting opening of a second commonly mounted fixture. The billboard and translucent sign are usually required to face the same direction; however, the first fixture, in order to illuminate the billboard, must be oriented to face in some other direction that depends upon the structural mounting location of the fixture assembly. A most convenient positioning of the assembly for this application is to place the two fixtures with their linear axes in parallel and transversely-spaced relation, and to permit both fixtures to be selectively rotatable over a full 360.degree. range in order to accommodate all possible mounting locations.
For many applications it is desirable to permit two linear reflected lighting fixtures, of the same or different length, to be assembled in a manner whereby a first fixture is secured to a second fixture so that the longitudinal axis of the first fixture can be positioned in substantially any orientation.
U.S. Pat. Nos. 4,204,274 (Luderitz) and 4,528,618 (Bitsch) disclose typical prior art lighting fixture assemblies in which two elongated lighting fixtures are mounted in spaced parallel orientation, and wherein both fixtures are rotatable about respective parallel axes. However, the very nature of the mounting or fixture structure in these assemblies precludes rotation of either fixture over a full 360 range. This severely limits the flexibility of these assemblies for optimal outdoor illumination and display applications. This limitation should not be surprising in view of the fact that both the Luderitz and Bitsch structures are designed for indoor use (i.e., as a wall light in a hospital room in the case of Luderitz, and as a desk or work table lamp in the case of Bitsch). I am unaware of any lighting assembly (for indoor or outdoor use) having two (or more) linear reflected lighting fixtures mounted so that either or both can be selectively rotatable about respective spaced parallel axes through a complete 360.degree. range. Moreover, I am unaware of any such assembly, for outdoor illumination or display applications, having even the limited fixture positional flexibility achieved by the Luderitz and Bitsch indoor units.
As noted above, it is also desirable to provide optimal positional adjustable for linear reflected lighting fixtures in an assembly wherein the fixture axes are not necessarily in spaced parallel relation. This feature is desirable for many outdoor illumination and display applications. In U.S. Pat. No. 3,062,952 (Harling) there is disclosed an outdoor street lighting assembly wherein two elongated fixtures are mounted for selective individual rotation about respective intersecting axes. This fixed orientation of the rotational axes severely limits the flexibility of overall illumination patterns and, thereby, limits applications for which the Harling unit may be employed. Moreover, although the fixtures in the Harling unit might each be selectively rotated over a 360.degree. range, the required intersecting orientation of the rotation axes precludes use of this unit for many display and illumination applications.
In addition to providing selectively variable illumination patterns by positionally adjusting individual fixtures, it is often desirable to selectively adjust the size of the light-emitting openings of linear reflected lighting fixtures used for display applications so that the size of the display sign may be changed as desired. It is also desirable to selectively adjust the directivity pattern of light emitted from a linear reflected lighting fixture, irrespective of the position of the fixture in an assembly or array of fixtures. To my knowledge, little or no attention has been given to these functions in the field of outdoor illumination and display lighting.